Apparatus for the pneumatic separation of materials



Nov. 17, 1936. 2,060,966

APPARATUS FOR THE PNEUMATIC SEPARATION OF MATERIALS F. ALLARDY Filed Jan. 8, 1955 INVENTOR D M? A a L N L R Aflm 5 m O. 0/ NY A W Patented Nov. 17, 1936 UNITED STATES TE FEE APPARATUS FOR THE PNEUMATIC SEPARATION OF MATERKAILS Francois Allard, Mont-sur-Marchienne, Belgium 9 Claims.

The present invention relates to the pneumatic separation, into their elements of different specific weight, of coals, ores and the like, travelling on an inclined perforated table supplied with air under pressure from below. The object of my invention is to obtain a more complete separation and to ensure a higher efficiency in an economical manner by improved use of the separating action of the air pressure.

According to my invention such results are achieved, by creating, in the moving bed of material on the table, alternating zones of constriction and expansion which aiTect both the progression of the material travelling on the table and the air current passing through the bed of material substantially at right angles to the direction of travel of said bed. The bed of material is thus thoroughly stirred up, whilst variations of pressure occur therein and assist the rapid and thorough separation into elements of different densities without any rough treatment which might break up the materials. According to an other feature of my invention, the rapidity of the separation is further enhanced by compelling the stream of material and the air current to follow zig-zag paths through the constricted and expanded zones or areas.

A simple method of providing such zones consists in mounting on the perforated table obstacles arranged to form therebetween wide and narrow passages in alternating relations, in the direction of travel of the stream of materials as well as in the transverse direction followed by the air current blown through the material. For this pur- 5 pose I preferably make use of narrow and long obstacles such as bars inclined in the direction of travel of the material in such manner as to intersect the air current passing through the bed of material. The inclination of the bars, which also assists in lifting the material subjected to air pressure, and the width of the passages between the obstacles, may be adjustable in accordance with operating conditions.

The bars are advantageously formed with a cross-section afiording the least resistance to the stream of material, and the said bars are preferably arranged in alternate checkered relationship on the table, in order to obtain a sufficiently slow flow of material and the maximum efficiency of the constrictions and expansions. At the delivery end of the table, a series of superposed knives or blades of adjustable width in the direction of travel of the material divide the bed into layers corresponding to the strata formed through the ,55 pneumatic separation.

The appended drawing shows diagrammatically, by way of example, a separating apparatus according to my invention.

Fig. 1 is a longitudinal section through the apparatus,

Fig. 2 is a partial longitudinal horizontal section,

Fig. 3 is an enlarged cross-section of one of the bars or obstacles, and

Fig. 4 is a similar view through a hollow bar 10 of adjustable width.

Fig. 5 is a detail view illustrating a modification.

As shown in Fig. 1, the apparatus comprises a perforated table l sloping down from front to 15 rear, arranged above an air pressure chamber 2 and provided with upturned ledges 3 so that the table has the general appearance of a trough. Bars 4 of prismatic triangular shape, mounted in checkered relationship on table I, are supported 20 at their upper end on cross members 5 secured to the top of the ledges 3. The said bars slope upwardly towards the rear or delivery end of the table and they form with said table in the illustrated embodiment, an angle of about 45, which however may be varied. For this purpose, the foot of each bar may be pivoted to the table by means of a hinge or of a flexible member such as a rubber base, whilst the cross-members 5 may be movable.

The material to be separated into its elements of different specific weight is fed to the table from the hopper 6, whence the delivery is adjusted through a slide '6. In order to assist the exit of the material from the hopper as may be required 35 by the nature of said material, I may admit air under pressure through the perforated bottom 8 of the hopper, the amount of air admitted being regulated by means of a pivoted valve 9 controlling the corresponding portion of the air tank or 4p chamber 2.

The material fills the shoot formed between the ledges 3 up to a level .1: depending on the position of slide 1 and on the resistance encountered through the stream of material flowing between 5 the obstacles or bars 4 which extend through the bed of material and form therein zones of constriction a and of expansion b, as illustrated in Fig. 2. It will readily be understood that the veins of material travelling along table I must 50 wind in between bars 4 as shown by the arrows y in Figure 1, whilst the air under pressure blown through the perforations of table I into the bed of material encounters the said inclined bars 4 and is also subdivided into veins which are obliged to follow a sinuous path as shown by the arrows 2. Moreover, the moving material is not only lifted by the air pressure, but it is also raised by the inclined bars, which act in the manner of ploughshares and may have bases of that shape, so that the material is lifted in narrow throttled veins in the constricted intervals between the bars forming the zones (1 and descends and widens out in the expansion zones b, and so forth. To such mechanical action, must be added the action of the variations of pressure created by the constrictions and expansions of the air currents or veins in the above mentioned Zones a and b forming centres of high and low pressure in the zones in which the materials are respectively throttled and allowed to expand. It is obvious that these two concurring actions assist in the rapid and thorough separation into elements of different densities after a short travel of the materials.

Figs. 2 and 3 show the section of the bars 4, shaped so as to offer the least resistance to the current of material, with the wide curved line of the prismatic bar facing upstream and the sharp edge pointing downstream. Fig. 4 shows a hollow bar of substantially similar shape which can be expanded, as its two halves 4a, 4b pivot about a hinge 4c in order to make the bar thicker or thinner as shown in dotted lines. In this manner I may at will vary the free passage remaining in between the bars and I may thereby adjust the flow of material as well as the ratio between the zones of constriction and expansion.

As previously mentioned, the inclination of the bars may also be varied. The adjustment of the inclination of the bars and/or of the distance in between the bars may be effected for each bar separately, or for all the bars together, or for one or several rows or groups of bars together.

I thus am enabled to control to a great extent the flow, the agitation and the thickness of the bed of material, as well as the conditions of operation of air within said bed, as required in accordance with the nature and the state of said material, in order to obtain the hightest efficiency of the separating apparatus in each particular case.

Beyond the last bars 4, the perforated table I is provided with a bare portion [0 to which the supply of air under pressure may be adjusted by means of a flap valve I I controlling the adjacent portion of the air chamber 2. Such adjustment enables me to retard or to accelerate as desired the current of material flowing towards the dividing knives or blades located near the outlet of the table. Fig. 1 shows a lower knife I2 arranged at the level of the table, and an upper knife [3 arranged above and in front of said first knife. It is obvious that a larger number of superposed knives might be provided in case it were desired to separate the material into more than two layers.

Every knife comprises two overlapping blades, i. e. an auxiliary blade lZa or I3a arranged behind and below a main blade I2 or I3 and movable in its own plane relatively to said main blade in order to increase or reduce the length of the knife, thereby varying the slope of the outgoing materials, said blades I2a and [3a being provided with an adjustably inclined plate I2b, I3b, if desired. In order to avoid too rapid motion of the materials on the knives it is advisable to make the upper surfaces of the blades and/or plates uneven for instance by recessing said surfaces or mounting metal wire netting thereon. If the sliding movement of the material on the blades is too slow, the bladesmay be reciprocated in order to accelerate such motion.

When the obstacles 4 are formed of tubular bars it may be advantageous to provide perforations M in one or more lateral faces of the portion of the bars which projects into the bed of material for the purpose of injecting therein air under pressure, which may be supplied for example through the top of the bars from a suitable air pressure supply I5 (Fig. 5).

The invention of course is not limited to the forms and to the details of the embodiments described and illustrated merely by way of example, and modifications may be effected without departing from the scope of appended claims.

I claim:

1. An apparatus for the pneumatic separation of coal, ores and the like, comprising in combination a stationary inclined table, said table having perforations in its inclined surface, means for blowing air through the perforations in said table, and parallel bars on said table inclined upwardly towards the delivery end of said table, each of said bars being surrounded with perforations.

2. An apparatus for the pneumatic separation of coal, ores and the like, comprising in combination a stationary inclined table, said table having perforations in its inclined surface, walls along the longitudinal sides of said table, means for blowing air through the perforations in said table, and parallel bars on said table of substantially the same height as said walls, said bars being inclined upwardly towards the delivery end of said table, said table having perforations both in front of and behind each of said bars.

3. An apparatus for the pneumatic separation of coal, ores and the like, comprising in combination a stationary inclined perforated table, means for feeding the material to said table, means for regulating the delivery of material to said table, means for blowing air through said table, and rows of inclined bars on said table, said bars having a substantially triangular cross-section and extending upwardly towards the delivery end of said table.

4. An apparatus for the pneumatic separation of coal, ores and the like, comprising in combination an inclined perforated table, means for feeding the material to said table, means for blowing air through said table, successive rows of inclined bars on said table obstructing the progress of the material along said table, the inclination of said bars being in opposite direction to the inclination of said table, and adjustable cross-pieces for varying the inclination of said bars with respect to said table.

5. An apparatus for the pneumatic separation of coal, ores and like material comprising in combination, an inclined perforated table, means for feeding the material to the top of said table, means for blowing air through said table, and inclined bars arranged in alternate relationship across the path of the material along said table, and means for varying the width of said bars.

6. An apparatus for the pneumatic separation of coal, ores and like material, comprising in combination an inclined perforated table, means for feeding the material to the top of said table, means for blowing air through said table, and rows of inclined bars arranged in alternate relationship across the path of the material along said table, said bars comprising a longitudinal hinge and two overlapping parts pivotally connected by said hinge and adapted to be moved relatively to each other in order to vary the width of said bars.

7. An apparatus for the pneumatic separation of coal, ores and like material, comprising, in combination, an inclined perforated screen, longitudinal side Walls for said screen, means for feeding the. material to the top of said screen, means for blowing air through said screen, parallel rows of bars on said screen inclined at an angle adapted to lift the material advancing along said screen, said bars extending upwardly substantially to the same height as said side walls, and means for varying the inclination of said bars with respect to the horizontal.

8. An apparatus for the pneumatic separation of coal, ores and like material, comprising, in combination, a stationary inclined perforated screen, means for feeding the material to the top of said screen, walls extending along the longitudinal sides of said screen, inclined bars extending as high as said walls adapted to check the progress of the material along said screen and. the passage of air through said material, said bars being inclined upwardly towards the delivery end of said table, and means at the bottom of said screen for separating the material delivered thereby, said separating means comprising adjustable blades arranged substantially parallel to said screen.

9. An apparatus for the pneumatic separation of coal, ores and like materials, comprising in combination, an inclined perforated tab-1e, means for feeding the material to the top of said table, means for blowing air through said table, rows of inclined bars on said table, said bars being inclined upwardly towards the delivery end of said table, the lower portions of said bars extending through the path of the material along said table, said bars being hollow and having perforations in the lower portions of their walls, and an air pressure supply connected with said hollow bars.

FRANQOIS ALLARD. 

